In this description, the term “chart” refers to a ranking of content according to popularity over a given period of time or according to editorial expertise. Examples of charts published in the music industry include: the Bilboard 100, MW Club Charts, Hot 100 or Top 40. Charts exist for other types of content and the term used herein is not intended to be limited to music unless expressly so limited. Charts may be compiled for example on different measures of popularity, for example retail purchases, download or streaming.